The present invention relates to an improvement for a length or angle measuring system of the type which comprises a scale carrier body and a measuring scale, wherein the scale is connected to the carrier body so as to be slightly shiftable with respect thereto.
German Pat. No. 27 12 421 discloses a prior art length measuring device in which a measuring band which operates as a scale is mounted in a groove-type recess in a scale carrier body such that the measuring band is slidable in the recess and the measuring band is fixed to the carrier body at one end.
Such measuring systems raise certain design problems. On the one hand, the tolerance between the dimensions of the groove and the dimensions of the measuring band should be small in order to preserve the required degree of measuring accuracy. On the other hand, measurement tolerances should be established as generously as possible in order to minimize manufacturing costs. However, since close dimensional tolerance takes precedence, because of the higher measuring accuracy obtainable when close tolerances are used, friction problems typically occur when the measuring band is slid into the groove of the scale carrier body. Furthermore, friction problems can occur in operation at a later time, when by reason of temperature fluctuations the scale and the scale carrier body expand differently, causing relative movement therebetween. In order to preserve high measuring accuracy it is important to minimize friction between the measuring band and the scale carrier body that can, under some circumstances, result in measurement errors. For example, in the event of relative movement between the measuring band and the carrier body, frictionally caused measuring errors can result solely through the weight of the measuring band itself.